The amount of air pressure in an automobile tire is important for a number of reasons. If the air pressure is too low the friction of the tire on the ground is increased, resulting in lower gas mileage. This increased friction produces more heat from the tire rolling on the ground and can cause the tire to disassemble. If the pressure is too high it is possible for the tire to explode and cause injury. In the case of pressure being outside of an optimal range the tire will not wear evenly resulting in a shortening of the expected life of the tire. Ideally tire pressure should be checked when gas is being added to the vehicle but this is not always the case. While this is an ideal situation, the pressure in most tires are only checked when the oil is being changed.
Part of the reason for people not checking the pressure in their tires on a regular basis is the difficulty involved in locating a tire pressure gauge, removing the cap on each tire, checking the pressure and re-installing the cap. To eliminate the problem associated with using a pressure gauge to check the pressure on a tire several devices have been patented that provide for a valve cap or cover with an integrated pressure indicator. While this has made it easier to visually check the pressure in each tire, the pressure indicator needs to be removed to add air to the tire, and the filled pressure is then determined after replacing the valve cover. A simpler solution is to provide a tire stem or tire stem extension with an integrated pressure indicator. Some patents have been issued on combination valve stem and valve stem adapters with integrated pressure indicators. The bulk of these devices have the pressure indicator existing concentric with the fill line. While these provide the function, their construction is complex and the indicator window is not always placed in an ideal location for viewing.
Examples of patents that show or describe this type of configuration are with U.S. Pat. No. 6,293,297 issued on Sep. 25, 2001 to Maldonado et al. and U.S. Pat. No. 4,901,747 issue on Feb. 20, 1990 to Enrique M. Yabor. In Maldonado the device threads into an existing valve stem and in Yabor the device is a valve stem. Both of these patents show and describe a device where the indicator is concentric with the fill line. These devices are not made with a branch from the filler line making alterations to the construction possible. The branch allows the filler line to be constructed at various angles and with various lengths to optimize the device based upon the vehicle the device will be placed into. Other patents have been issued where the fill line and the indicator is not concentric. Some exemplary examples of these patents are described herein.
U.S. Pat. No. 5,979,232 issued Nov. 9, 1999 to Halcomb discloses a tire pressure filler with a gauge where the pressure indicator is located in a parallel relationship to the fill valve. In this patent the filler screws onto a standard tire valve stem, but the filler is a different size from the valve stem. It is further possible for the filler port to exist in a location that blocks the view of the sighting hole. This device is further not intended to be used as a valve stem, and the length of the device is fixed thereby reducing installation options.
U.S. Pat. No. 5,503,012 issued Apr. 2, 1996 to Masoud Rabizadah discloses a combination filler and pressure indicator where the indicator gauge is located along side the filler port. In this patent the indicator is a ball that moves within a sight glass. The device is further configured as a valve stem. While this patent discloses the basic components, it is not configurable to different lengths, it is installable in a condition where the sight glass is not visible, and is not usable where multiple or dually tire are mounted.
Various other improvements have been made to improve the overall operation of the tire filler and pressure indicator that include internal features that are part of the pressure indicator. These features further improve the manufacturability of the apparatus and most if not all of these features are not claimed or described in the prior art.
What is needed is a tire filler with an integrated pressure indicator that is manufacturable to various lengths with improved design and construction features that allow it to be made in a cost effective and configurable manner. The proposed application provides these features and is described in detail herein.